Irreversible inactivation of 3-hydroxy-3-methylglutaryl-CoA reductase by H2O2

Omkumar, RV and Ramasarma, T (1993) Irreversible inactivation of 3-hydroxy-3-methylglutaryl-CoA reductase by H2O2. In: Biochimica et Biophysica Acta (BBA) - General Subjects, 1156 (3). pp. 267-274.

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Abstract

A concentration-dependent inactivation of 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase was found on reincubation of rat liver microsomal preparations with H2O2 and at lower concentrations in the presence of KCN which inhibited the contaminating catalase. The inactivation was not affected in the presence quenchers of hydroxyl radicals and singlet oxygen and was also obtained when H2O2 was added during the reaction. HMG-CoA, but not NADPH, partially protected the enzyme from H2O2-inactivation. Even at high concentration DTT was unable to reverse this inactivation. The soluble 50 kDa-enzyme was similarly inactivated by H2O2, and the tryptic-digest of the inactivated protein indicated the presence of a disulfide-containing peptide. The results support the view that H2O2 by directly acting on the catalytic domain possibly converts an active thiol group to an inaccessible disulfide and irreversibly HMG-CoA reductase.

Item Type:	Journal Article
Publication:	Biochimica et Biophysica Acta (BBA) - General Subjects
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	HMG-CoA reductase;H2O2-inactivation;Hydroxyl radical;Thiol oxidation.
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	11 Feb 2011 06:35
Last Modified:	11 Feb 2011 06:35
URI:	http://eprints.iisc.ac.in/id/eprint/35518

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